This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Many accessories for electronic devices are getting smaller and smaller in size. Such accessories are, for example, hands-free headsets for e.g. mobile terminals. Also other accessories for mobile terminals and other portable devices may be designed so that the size of the accessories can be decreased.
Not only the size but also the current consumption in active mode such as talk and music listening mode has recently been decreasing and this trend is still going on.
Recently, very small headsets have been developed for portable devices. The smaller size of the accessories may cause that the size of batteries for such accessories should also become smaller. Current consumption while talking has become smaller so that it is possible to use smaller sized batteries and still achieve long enough operating time of a full charged battery.
Many wireless headsets use lithium ion batteries which need battery protection circuitry for safe charging and good battery lifetime. Recently, some accessories have been designed to use lithium polymer batteries which may provide more capacity than lithium ion batteries or other batteries of the same size suitable for small accessories. In other words, the energy density of lithium polymer batteries may be higher than the energy density of e.g. lithium ion batteries.
Batteries tend to discharge although they were not connected to any load. This feature may also be called as a self discharge. Different types of batteries may have different discharging properties so that some battery types may maintain the charge longer than some other battery types. The battery self discharge may be relatively worse in small batteries than in large batteries.
The storage time of batteries when shipped from a factory to a supply chain and to an end user may be several months. It is therefore intended to minimize more the power consumption in a power off state to prevent permanent damage to a battery.